21945125 has 12 divisors (see below), whose sum is σ = 27453036. Its totient is φ = 17514200.

The previous prime is 21945101. The next prime is 21945137. The reversal of 21945125 is 52154912.

It is a powerful number, because all its prime factors have an exponent greater than 1 and also an Achilles number because it is not a perfect power.

It can be written as a sum of positive squares in 2 ways, for example, as 702244 + 21242881 = 838^2 + 4609^2 .

It is a de Polignac number, because none of the positive numbers 2^k-21945125 is a prime.

It is a super-2 number, since 2×21945125² = 963177022531250, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 52166 + ... + 52584.

It is an arithmetic number, because the mean of its divisors is an integer number (2287753).

Almost surely, 2^21945125 is an apocalyptic number.

21945125 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21945125 is a deficient number, since it is larger than the sum of its proper divisors (5507911).

21945125 is an frugal number, since it uses more digits than its factorization.

21945125 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 853 (or 424 counting only the distinct ones).

The product of its digits is 3600, while the sum is 29.

The square root of 21945125 is about 4684.5624128621. The cubic root of 21945125 is about 279.9707665058.

The spelling of 21945125 in words is "twenty-one million, nine hundred forty-five thousand, one hundred twenty-five".